声压级 谱 1/3 倍频程 matlab代码

声压级：声压级是指声音的强度程度，通常用分贝（dB）来表示。分贝越高，声音就越响。

谱：谱是指信号在频域上的表示，一般包括幅度谱和相位谱。

1/3 倍频程：在信号处理中，1/3 倍频程是指信号的有效频率范围，在此范围内信号能够被恰当地采样。

Matlab 代码：

1.计算声压级：

function SoundPressureLevel = SoundPressureLevelCalculator(y, y_reference)
% y:音频信号
% y_reference:参考音量

% 将音频信号转换为可选的区间内零平均值
y = y - mean(y);

% 音频信号的RMS幅值
RMS = sqrt(mean(y.^2));

% 计算参考音量的声压级
y_reference = y_reference - mean(y_reference);
RMS_reference = sqrt(mean(y_reference.^2));
SoundPressureLevel_reference = 20*log10(RMS_reference/20e-6); % dB SPL

% 计算音频信号的声压级
SoundPressureLevel = 20*log10(RMS/20e-6) - SoundPressureLevel_reference; % dB

2.计算频域谱：

function [amplitude_spectrum, frequency_axis] = FrequencySpectrumCalculator(y,fs)
% y:音频信号
% fs:信号的采样率

% 快速傅里叶变换
L = length(y);
Y = fft(y);
P2 = abs(Y/L);
amplitude_spectrum = P2(1:L/2+1);
amplitude_spectrum(2:end-1) = 2*amplitude_spectrum(2:end-1);
frequency_axis = fs*(0:(L/2))/L;

3.计算1/3倍频程：

function thirdOctaveBandFrequencies = ThirdOctaveBandFrequencies(frequencyRange, numBands)
% frequencyRange:频率范围
% numBands:数量

% 以3为底的对数计算，计算频率范围的的上限和下限
lowerFrequencyLimit = 2.^(-1/6)*frequencyRange(1);
upperFrequencyLimit = 2.^(1/6)*frequencyRange(2);

% 计算频带的边界
thirdOctaveBandFrequencies = zeros(1, numBands);
thirdOctaveBandFrequencies(1) = lowerFrequencyLimit*sqrt(2);
for ii = 2:numBands
thirdOctaveBandFrequencies(ii) = thirdOctaveBandFrequencies(ii-1)*sqrt(2);
end
thirdOctaveBandFrequencies(thirdOctaveBandFrequencies > upperFrequencyLimit) = [];
thirdOctaveBandFrequencies = [lowerFrequencyLimit, thirdOctaveBandFrequencies, upperFrequencyLimit];